HU Bass Up?

OK, this is kinda hard to explain, but I am going to try. I have a Blaupunkt Austin HU with A JBL 600.1 Amp and a Pair of Shivas in a Sealed box. Righ now I think that I have the Low pass filter set too high (I am guessing about at 90, its hard to tell on JBL amps), some songs get sloppy at times. I turned the Low pass down (to probably about 75 or so), but then I lost a lot of Volume that I had with the really low notes that I had with the filter Higher. (I would think that the lower, like 30-50 notes, would be the same volume at both these settings, but they were not). How would I fix this? I wish that I have a sub control on the HU by the BLuapunkt unit that I have has very little if any options. I was thinking about setting the low pass lower and either turning the bass up on the HU or adding some "Bass Boost" from the amp controls. What do you think? I hope you all understand my situation.

try to set the crossover at around 65hz (i know its hard to do so on a JBL amp). don't turn on the bass boost. all you're doing is adding some more audible distortion to the sub and at high volume, it will sound yucky. what do you mean sloppy? what kind of music do you listen to? how big is your box?

I had the cossover set low, but the volume of the the low beats was quite compared to the setting i have it at now (about 90). I listen to techno, rock, and rap. Songs like Eminem - Loose Yourself, Crystal Method to name some stuff, is the stuff that sounds sloppy. When I say sloppy, I am sayin that the bass lines kinda just roll together into one big bass noise, they are not very defined (gets like this just sometimes, on certain songs) I dont know if it is just the song that has a badd bass line, or my setup. I have about a 1.2 cf for each sub, it is then filled about 1/3 with pollyfill.

i think for the most part, its just some of the songs. i got that same constant vibration on some songs, and i had my lp at 40hz. but of course the higher you set your filter the more "sloppy" its gonna get.

1.2 cubic feet isn't nearly enough to get them to play a flat response (also bigger box tends to be more accurate). u have 2 option now:

1) build a new box ($20 MDF)
2) invert the subs and reverse the polarity to gain a little bit more internal volume.

eminem-lose yourself sounds kind of loose on my system also;)

the songs you listed don't really have a lot of low bass ....... mostly midbass